Ahead of a meeting at the Munich Security Conference between US Vice President JD Vance and Volodymyr Zelenskyy, Sir Keir said: "Nobody wants the conflict to continue and Ukrainians - more than anybody - want the conflict to end, but we must make sure Ukraine is at the heart of this.
"You can see that in the UK with the increased defence spending that we announced at the budget, our commitment to setting our path to 2.5% of GDP in defence, our work as part of the strategic defence review to determine the challenges, threats and opportunities that UK faces.
Responding to the changing international relations landscape, a No10 spokesperson said: "I think all European leaders agree that Europe needs to step up in terms of defence collaboration, defence spending.
But US Defence Secretary Pete Hegseth insisted a final deal would not include NATO membership for Ukraine or the return of Crimea, which was taken by Russia in 2014.
In Munich, British Defence Secretary John Healey reiterated that "there can be no negotiation about Ukraine without Ukraine".
